One-man saw for large beams; notes on motion and weights
A counterweight-driven saw, a crank-wheel and notes on sustaining motion, and a balance for testing weights
The main drawing shows an apparatus by which one man alone can saw any large beam into planks, its saw-teeth (Leonardo notes) turned toward the counterweight. Around it are jottings 'on the nature of motion': a crank-wheel prompts the observation that a wheel set spinning runs on after its mover lets go, yet to keep it turning the mover must always spend equal or greater effort since it tires by nature. A balance held level by a beam over a pulley (a - b - 100) illustrates a way to test a rule de ponderibus, and a small square is drawn below. A later hand has added a note in another language across the top of the sheet.
On this page
A saw for one man to cut large beams
The chief drawing is an apparatus letting a single man saw any large beam into planks, its frame worked against a counterweight. Leonardo adds only that the teeth of the saw should be turned toward the counterweight.
On the nature of motion: the crank-wheel
Under the heading 'on the nature of motion', a crank-wheel prompts Leonardo's reflection that a wheel set raging keeps turning after its mover abandons it. Because keeping it at that speed seems to cost little force, he concludes that to maintain the motion the mover must always be of equal labour, and the more so as it tires by nature.
Balance for testing a rule of weights (de ponderibus)
A balance held horizontal by a beam tied to a pulley, marked a - b - 100, is offered as a way to test a rule de ponderibus, that is, of weights. A small square is drawn nearby.